Adsorption and interactions of dentine phosphoprotein with hydroxyapatite and collagen

Dentine phosphoprotein (DPP) has been proposed to both promote and inhibit mineral deposition during dentinogenesis. The present study aimed to investigate the molecular interactions of DPP and dephosphorylated DPP (DPP‐p) with hydroxyapatite (HAP). Bovine DPP was purified and dephosphorylated by al...

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Bibliographic Details
Published in:European journal of oral sciences 2006-06, Vol.114 (3), p.223-231
Main Authors: Milan, Anna M., Sugars, Rachael V., Embery, Graham, Waddington, Rachel J.
Format: Article
Language:English
Subjects:
Absorption
Adsorption
Alkaline Phosphatase - chemistry
Animals
Cattle
Collagen - chemistry
Crystallization
dentine
Dentistry
Durapatite - chemistry
hydroxyapatite
Medicin och hälsovetenskap
mineralization
Phosphates - chemistry
phosphoprotein
Phosphoproteins - chemistry
Protein Binding
Protein Conformation
Temperature
Time Factors
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Summary:Dentine phosphoprotein (DPP) has been proposed to both promote and inhibit mineral deposition during dentinogenesis. The present study aimed to investigate the molecular interactions of DPP and dephosphorylated DPP (DPP‐p) with hydroxyapatite (HAP). Bovine DPP was purified and dephosphorylated by alkaline phosphatase to obtain DPP‐p. DPP and DPP‐p adsorption to HAP was determined along with their ability, when free in solution or bound to collagen, to influence HAP‐induced crystal growth. Absorption isotherms suggested that lower DPP concentrations (1.5–6.25 µg ml−1) demonstrated a reduced affinity for HAP compared with higher protein concentrations (12.5–50.0 µg ml−1). Dephosphorylated DPP had a much reduced affinity for HAP compared with DPP. Dentine phosphoprotein inhibited seeded HAP crystal growth, in a dose‐dependent manner, whilst removal of the phosphate groups reduced this inhibition. When bound to collagen fibrils, DPP significantly promoted the rate of HAP crystal growth over 0–8 min. Conversely, DPP‐p and collagen significantly decreased the rate of crystal growth over 0–18 min. These results indicate a major role for the phosphate groups present on DPP in HAP crystal growth. In addition, concentration‐dependent conformational changes to DPP, and the interaction with other matrix components, such as collagen, are important in predicting its dual role in the mineralization of dentine.
ISSN:0909-8836
1600-0722
DOI:10.1111/j.1600-0722.2006.00347.x